FR2501671A1 - PROCESS FOR THE PREPARATION OF 1,1-DICHLORO-4-METHYL-1,3-PENDIENE - Google Patents

Abstract

PROCESS FOR PREPARING 1,1-DICHLORO-4-METHYL-1,3-PENTADIENE. CHLORAL AND ISOBUTYLENE ARE REACTED, WHICH GIVES THE 1,1,1-TRICHLORO-2-HYDROXY-4-METHYL-3-PENTENE OF FORMULA I: (CF DRAWING IN BOPI) THAT WE DONE HIMSELF REACT WITH THIONYL CHLORIDE, PREFERABLY IN THE PRESENCE OF A CATALYST, WITHOUT SOLVENT OR IN AN INERT SOLVENT, THE REACTION GIVING 1,1,1,4-TETRACHLORO-4-METHYL-2-PENTENE WHICH IS FINALLY SUBMITTED REDUCTION. THE PROCESS ACCORDING TO THE INVENTION GIVES THE RESEARCH COMPOUND FROM SIMPLE STARTING PRODUCTS AND WITH AN ALMOST QUANTITATIVE YIELD.

Description

The invention relates to a method for the pre-

  partioning 1,1-dichloro-4-methyl-1,3-pentadiene.

  According to the invention, 1,1-dichloro-4-methyl-1,3-pentadiene is prepared by a process which is characterized in that the chloral is reacted.

  and isobutylene, this reaction giving the 1,1,1-

  trichloro-2-hydroxy-4-methyl-3-pentene corresponding to the formula I Cl OH C -C CH 3 CH 3 CH 3 CH 3 which is itself reacted with thionyl chloride, preferably in the presence of a catalyst, in the absence of solvent in an inert solvent, this reaction itself giving 1,1,1,4-tetrachloro-4-methyl-2-pentene

that we submit to reduction.

  1,1-Dichloro-4-methyl-1,3-pentadiene is the key intermediate in the

  synthesis of cyclopropane carboxylic acid esters.

  Among the known processes for its preparation, it is

  a process in which one starts from 1,1,1-trichloro-

  4-methyl-4-hydroxy-pentane itself formed by addition of 2-methyl-3-butene-2-ol and chloroform, and wherein

  water and hydrochloric acid or

  payment; another method in which the same dehydrohalogenation and dehydration compound is applied (R.F.A. Patent Application Nos. 2,536,503, 2,536,504 and 2,616,528). The disadvantages of these processes are that the compound formed in the course of chloroformic telomerization contains approximately

  15 to 20% of the isomer in which the trichloromethyl group

  it is not at the end of the chain. This impurity can not be separated by physical techniques

  and its reaction products cause im-

  during the purification of the valuable cyclopropanecarboxylic acid ester. In recent years, we have

  some processes for preparing 1,1-

  * dichloro-4-methyl-1,3-pentadiene in a tubular reactor

  operating continuously at a temperature of 400 to

  5000C. In these processes, the starting material is iso-

  butylene which is reacted in the presence of peroxide catalysts with either tri-chloroethylene or with 1,1-dichloroethylene (British Patent Nos. 1,532,676 and 1,531,733, German Patent Application Publication No. 2,629. 868). The disadvantage of this process lies first and foremost in that all the mixtures obtained in

  these conditions contain the desired product in

from 5 to 101- only.

  The process of Farkas (J. Farkas, P. Kohrim,

  F. Sorm: Coll. Czech. Chem. Common. 24 2230 (1959), de-

  Patent Application Publication No. 2,616,681) is a technically simple and inexpensive process for raw materials for preparing the desired product. In this

  process, the product is the mixture of the 1,1,1-isomers

  trichloro-2-hydroxy-4-methyl-pentene-3 and -4 formed by the reaction of Prins between isobutylene and chloral. AT

  from this mixture of isomers, the 1,1-dichloride is prepared

  ro-4-methyl-1,3-pentadiene by acetylation with oxygen, reduction with zinc and acetic acid, elimination and isomerization. The biggest disadvantage of this process

  in this case, to eliminate the acetoxy group by re-

  duction, it takes a lot of zinc, relatively expensive.

  The method according to the invention is based on the

  discovered that when chlorinated with thio chloride

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  1,1,1-trichloro-2-hydroxy-4-methyl-3-pentene which can itself be easily prepared from simple starting materials by the Prins reaction, the removal of SO 2 in the product intermediate is accompanied by a rearrangement of the alkyl groups

  with quantitative formation of 1,1,1,4-tetrachloro-4-

  methyl-2-pentene, which can itself be converted into 1,1-dichloro-4-methyl-1,3-pentadiene in almost quantitative yield by reduction techniques

usual.

  For the implementation of the process according to

  Preferably, the mixture of 1,1,1-trichloro-2-hydroxy-4-methyl-3-pentene and thionyl chloride in excess of 15 to 80 mol%, and preferably 1% by weight of dimethylformamide, is preferably used. of

  catalyst, without solvent or in an inert organic solvent.

  preferably in aromatic hydrocarbons or chlorinated aliphatic hydrocarbons at a temperature of 40 to 130 ° C., preferably 60 ° to 90 ° C., until the evolution of gas ceases; the excess of thionyl chloride and the organic solvent are then distilled off. The resulting product can be used for reduction without further purification; however, if it is necessary,

  purify it by distilling it under vacuum (before hydrogenation).

  catalytic reaction). The reduction is carried out by known techniques, preferably using amalgamated iron powder, aluminum or zinc in an alkanol (methanol, ethanol, isopropanol) which serves as a solvent,

  a temperature of 40 to 70 C, by catalytic hydrogenation

  (on a palladium on charcoal catalyst in an alkanol, acetone or acetic acid

  solvent at a temperature of 20 to 60 C or with a catalytic

  Raney nickel lysine respectively, in an alkaline

  yes, it serves as a solvent, in the presence of a base in

  equivalent to the amount of hydrochloric acid formed -

  preferably triethylamine or sodium carbonate

  potassium) or with sodium hydrosulphite in methanol containing sodium hydroxide in an amount equivalent to the amount of hydrochloric acid formed at a temperature of 60 ° C .; after filtering the reaction mixture and removing the solvent, isolating

  the product by vacuum distillation.

  The following examples illustrate the

  but without limiting its scope; in these examples, the indications of parts and percentages

  by weight unless otherwise indicated.

Example 1

  A mixture of 90.0 g (0.44 mol) of 1,1,1-trichloro-2-hydroxy-4-methyl-3-pentene and 350 ml of solvent (aromatic hydrocarbon or chlorinated aliphatic hydrocarbon) is heated to 60 ° -80 ° C. preferably 1,2-dichloroethane or benzene), 59.6 g (0.5 mole) of thionyl chloride

  and 1.0 ml of dimethylformamide and stirred at this temperature.

  until the release of gas ceases. We

  poured the reaction mixture into 400 ml of water and

  tralise with sodium bicarbonate. The organic phase is separated off and the solvent is distilled off. 91.0 to 95.8 g (93 to 98%) of the crude product are obtained as a residue. To purify the product, it is fractionated under an absolute pressure of

26 mbar.

  Yield: 86.0 - 88.9 g of 1,1,1,4-tetra-

  chloro-4-methyl-2-pentene (88-91%) boiling

-1200C / 26 mbar.

  IR (film): 3000, 1460, 1380, 1285, 1250, 1120, 1085, 960, 840, 775, 730 cm1 1H NiR (CDCl3), δmax: Me: 1.73s (64); CH = CH-: 6.27 d (14) 6.43d (14) 13C NMR (CDCl3): ppm7: Me: 32.2, Me2 CCI: 65.3, CCI: 9.40

CH = CH: 132.4, 137.8

Example 2

  A mixture of 90.0 g of 1,1,1-trichloro-2-hydroxy-4-methyl-3-pentene, 89.3 g of thionyl chloride and 1.0 ml of dimethylformamide is heated to boiling and further heating to boiling until the release of gas ceases. The excess thionyl chloride is distilled off and the residue is fractionated in vacuo.

  Yield: 88.0 g (90%) of 1,1,1,4-tetrachloro-

4-methyl-2-pentene.

Example 3

  It is heated to boiling for 2.5 to 3 hours.

  a mixture of 22.2 g (0.1 mole) of 1,1,1,4-tetrachloride

  4-methyl-2-pentene, 150 ml of ethanol, 4 g (0.15

  gram) of aluminum powder and 0.27 g (0.001 mol) of mercuric chloride; the solid substance is filtered and

  it is washed with methanol. The alcohol solutions are combined

  The solvent is distilled off and the residue is

under vacuum.

  Yield: 13.8 g (91%) of 1,1-dichloro-4-

  methyl-1,3-pentadiene boiling at 62-64 ° C / 26mbar.

Examples 4 and 5

  In these examples, we proceed as in the e-

  Example 3 but using as reducing agent

  iron powder and zinc powder; the re-

  The results obtained are reported below:

  example reducing agent 1,1-dichloro-4-methyl-1,3-

  pentadiene g% 4 8.2 g of iron powder 13.2 87 8.6 g of zinc powder 13.5 89

Example 6

  It is hydrogenated at room temperature and

  a mixture of 22.2 g (0.1 mole) of

  1,1,1,4-tetrachloro-4-methyl-2-pentene and 200 ml of isopropyl

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  panol on 1 g of 10% palladium on charcoal catalyst.

  good. When we have absorbed the equimolecular quantity

  of hydrogen, the catalyst is filtered off, the soil is distilled

  and the residue is fractionated under vacuum.

  Yield: 14.0 g (92%) of 1,1-dichloro-4-methyl-1,3-pentadiene Examples 7 and 8 In these examples, the procedure is the same as in Example 6 but respectively used

  as solvents, acetic acid and acetone. The re-

  - The results obtained are reported below:

  example solvent temperature, C 1,1-dichloro-4-methyl-

  1,3-Pentadiene Acetic Acid 60 12.6 83 Acetic Acid 30-35 15.0 86

Example 9

  It is hydrogenated under vigorous shaking at

  ambient temperature and at atmospheric pressure a mixture

  22.2 g (0.1 mol) of 1,1,1,4-tetrachloro-4-methyl-2-

  pentene, 200 ml of ethanol and 20.2 g (0.2 mole) of triethyl

  amine on 0.4 g of Raney nickel. When we absorbed the

  equimolar amount of hydrogen, the catalyst is filtered off

  The filtrate is concentrated to a final volume of 40 ml and 200 ml of water are added. The mixture is extracted twice with 70 ml of dichloromethane each time, the solution is dried in dichloromethane, and the mixture is removed.

  the solvent and the residue is distilled under vacuum (26 mbar).

  ? 3> t Yield: 12 6 g (835%) of 1,1-dichloro-4-

  m-'tyl-, 3-pentadiene. EXAMPLE 10 In this example, the procedure is the same as in Example 9 but the triethylamine is replaced

  by 0.2 moles of potassium carbonate.

  Yield: 12.7 g (84%) of 1,1-dichloro-4-

methyl-1,3-pentadiene.

Example 11

  In a mixture of 22.1 g (0.1 mol) of 1,1,1,4-tetrachloro-4-methyl-2-pentene, 100 ml of methanol and 12.0 g of sodium hydrosulfite are added dropwise.

  30% sodium hydroxide solution containing 8 g of hy-

  The mixture is stirred at room temperature for 3 to 4 hours, the mixture is concentrated to a quarter of its original volume, 200 ml of water are added and the mixture is stirred at room temperature.

  The mixture is extracted twice with 100 ml of dichloro-

  methane each time. The extract is dried, distilled

  the solvent and the residue is fractionated under vacuum.

  Yield: 12.8 g (84%) of 1,1-dichloro-4-

methyl-1,3-pentadiene.

r

Claims (7)

  1 - Process for the preparation of 1-ldichloro-4-   methyl-1,3-pentadiene, characterized in that chloral and isobutylene are reacted to give 1,1,1-trichloro-2-hydroxy-4-methyl-3-pentene corresponding to the formula I Cl \ .. Cl-7C - CE - CH = C - Cil -   CH 3 CH 3 which is itself reacted with thionyl chloride, preferably in the presence of a catalyst, without a solvent or in an inert solvent, this reaction yielding 1,1,1,4-tetrachloro-4- 2-methylpentene which is subjected to reduction.   2 - Process according to claim 1, characterized   in that the pentene of formula I is reacted with thionyl chloride in a molar excess of at 80%.   3 - Process according to claim 1 or 2,   characterized in that the reaction pentene is reacted   mule I with thionyl chloride in the presence of 1% by weight of dimethylformamide which serves as a catalyst at a temperature of 40 to 130 C and preferably 60 at 90 C.   4 - Process according to claim 1,   characterized in that the 1,1,1,4-tetrachloro-4-   reductive dehydrohalogenation methyl-2-pentene using amalgamated metal powder (zinc, iron, aluminum) in alkanol solvents at a temperature of 60 3 to 900C.   Process according to claim 1, characterized in that the reductive dehydrohalogenation of 1-1,1, 4-tetrachloro-4-methyl-2-pentene is carried out using 0 167 1 of basic sodium hydrosulfite.   6 - Process according to claim 1,   characterized in that the reductive dehydrohalogenation of 1,1,1,4-tetrachloro-4-methyl-2-pentene is carried out by catalytic hydrogenation in acetic acid, acetone or alcohol-type solvents at a temperature of at 600C.   7 - Process according to claim 6,   characterized in that, for the reduction, a palladium catalyst on a bone charcoal support is used at a metal content of 5 to 10%.   8 - Process according to claim 6,   characterized in that, for reduction, a Raney nickel skeleton catalyst and bases are used.   organic or mineral - preferably trimethyl   mine or potassium carbonate -.